Added EIP 96 blockhash getter

eip_96_blockhash_getter.se

@@ -0,0 +1,23 @@
+# Setting the block hash
+if msg.sender == 2**160 - 2:
+    with prev_block_number = block.number - 1:
+        # Use storage fields 0..255 to store the last 256 hashes
+        ~sstore(prev_block_number % 256, ~calldataload(0))
+        # Use storage fields 256..511 to store the hashes of the last 256
+        # blocks with block.number % 256 == 0
+        if not prev_block_number % 256:
+            ~sstore(256 + (prev_block_number / 256) % 256, ~calldataload(0))
+        # Use storage fields 512..767 to store the hashes of the last 256
+        # blocks with block.number % 65536 == 0
+        if not prev_block_number % 65536:
+            ~sstore(512 + (prev_block_number / 65536) % 256, ~calldataload(0))
+# Getting the block hash
+else:
+    if block.number - ~calldataload(0) <= 256:
+        return(~sload(~calldataload(0) % 256))
+    elif not block.number % 256 and block.number - ~calldataload(0) <= 65536:
+        return(~sload(256 + (~calldataload(0) / 256) % 256))
+    elif not block.number % 65536 and block.number - ~calldataload(0) <= 16777216:
+        return(~sload(512 + (~calldataload(0) / 65536) % 256))
+    else:
+        ~invalid()